I’ve been digitizing old family photos for a few years now. When I started, I used an Epson flatbed scanner – an Epson Perfection V550 – which scanned negatives as well as photographs. Later I bought a better Epson scanner, the V850, which is a higher-end model. I like these scanners, but I was a little disappointed with the sharpness of the smallest details. A few years back, I tried digitizing slides and negatives with a digital camera (a Panasonic Lumix GH5). I also used it to digitize some printed photographs and documents. The results from the camera seemed pretty good to me, so I thought I’d do a detailed comparison of the two methods.
For the subject, I wanted something with very fine lines. I was going to use a banknote, but the scanning software didn’t like that. Instead, I used an old Canadian stamp.
Using the Epson scanner, I scanned the stamp at various resolutions – 200, 300, 400, 600, 1200, 2400, 3600, and 6400 dpi, which is the maximum resolution for this scanner. Of course, files become much larger as the resolution increases. The scan of stamp at 200 dpi took up a fraction of a megabyte. At 6400 dpi, it was 216 megabytes. Scanning also becomes proportionally slower as the resolution is increased – the highest resolution scan of this small stamp took 1 minute 23 seconds.
Here’s a section from scans of the stamp taken at different resolutions. You can see a steady improvement in quality as we move up from 200 dpi to 1200 dpi.
Going further, there’s a small nudge in quality from 1200 to 2400, but after that, even zooming in very close on the original files and looking at the finest details, I can’t see any further improvement in quality, although the files become much larger as the resolution increases. The maximum quality seems to be somewhere between 1200 and 2400. You can click on the images to see a larger version. These are just JPEGs, but they are representative of the original files.
At about 1200 dpi, the camera image is roughly comparable to the highest image quality from the scanner. At 3200 dpi, the camera is still picking up more details. For example, there’s a tiny H in the right corner of the stamp. Here it is digitized by the camera at 3200 dpi and by the scannera at 6400 dpi.
As you can see, the camera picks up finer details, including the grain of the paper, texture which is a blur on the scanner. Again, this shows that the maximum effective resolution of the scanner is significantly lower than 3200 dpi.